Synthetic wood

ABSTRACT

A synthetic wood material and method are disclosed, including providing a plurality of continuous glass fibers oriented substantially in the longitudinal axis and coated with a resorcinol modified phenolic resin binder substantially free from catalyst. In one aspect, the synthetic wood material is oxidatively treated to restore color. In one aspect, the fibers and binder are precoated with a furfuryl alcohol resin prior to the pultrusion step to form the synthetic wood.

This application is a division of Ser. No. 09/132,092 filed Aug. 10,1998.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a synthetic wood composition, a method ofpreparation for forming such a synthetic wood composition, and anarticle made from such a synthetic wood composition. In one aspect, thisinvention relates to a novel synthetic wood article resistant to attackby fungi and termites and which is efficient and safe to manufacture andproduce.

2. Background

Natural wood is susceptible to attack by fungi and termites. Naturalwood is particularly susceptible to attack by fungi and termites, afterhaving become seasoned, or when the wood is held in contact with moistearthen ground. The wood becomes degraded and loses important structuraland decorative features that it had before breaking down from the fungior termite attack.

Prior attempts to protect natural wood have used chemical treatments onthe wood to circumvent the shortcomings of natural wood, when seasoned,to become susceptible to attack by fungi and termites. Such priorchemical treatments on the natural wood involve procedures such aswolmanizing and the like. Wolmanizing is the application of copper,chromium, and arsenic compounds under pressure to cure the wood and actas a preservative. These prior chemical treatments have environmentaldistaste because of the toxic nature of the chemicals used.

Another drawback of natural wood is that it remains unsuitable forapplications in areas where fire proofing is desired.

Another drawback of natural wood is that defects such as knots, warps,and voids are a disadvantage aesthetically.

Another drawback of natural wood is that defects such as knots, warps,and voids degrade the mechanical properties of the wood.

INTRODUCTION TO THE INVENTION

An attempt to circumvent the degradation problems of natural wood caninvolve wood substitutes made using petroleum-based ingredients such aspolyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride(PVC), and the like. Typically when using these petroleum-basedingredients, recycled stock is mandated by the high cost of new,never-before-used stock. Such new stock typically is not economicallyjustified even in view of preferred resultant mechanical propertiesprovided by the composites produced from new stock. So recycled stock isused.

However, over time, it has been found that recycled stock has a tendencyto suffer creep in structural applications.

Although recycled stock formulations can be made to be resistant tofungal or termite attack, the formulations such as polyethylene (PE) andpolyethylene terephthalate (PET) are not fire resistant. The recycledstock formulations such as polyethylene (PE) and polyethyleneterephthalate (PET) require the expensive assistance of high additivefiller loads to attain any appreciable fire proofing.

In the case of polyvinyl chloride (PVC), recycling poses environmentalconcerns.

Highly desirable would be a synthetic wood composition, or composite,that has the structural features and the aesthetic visual appeal ofwood, but not the shortcomings of wood or its substitutes as availablefrom the disclosures of the prior art.

Examples of synthetic compositions are disclosed in Soda et. al. U.S.Pat. Nos. 3,720,572 and 3,936,518, McCaskey, Jr., et. al. U.S. Pat. No.4,044,185, Anstadt et. al. U.S. Pat. No. 4,141,944, and Shinomura U.S.Pat. No. 3,935,047. Although such formulations are resistant to fungalor termite attack, with the exception of PVC, these formulations are notfire resistant. They require the expensive addition of high filler loadsto attain any appreciable fire proofing. Recycling of PVC posesenvironmental concerns.

Coupled with a tendency to creep, these formulations are unsuitable foruse in structural applications.

Walls U.S. Pat. No. 3,662,446 uses a steel/fiberglass rod core shaftcovered by a foamed layer. Upon exposure to cyclic weather conditions,the pores in the foamed layer act as sites of extensive frost heavingand the attendant mechanical damage to the products.

Armellini U.S. Pat. No. 5,536,541 employs materials of an indeterminatenature, and the Armellini method involves a complicated multi-stepassembly.

Hindersinn U.S. Pat. No. 4,419,400 discloses pultruding glass fiber witha glycol modified phenolic resole. Handling of the resin duringpultrusion exposes workers to the residual formaldehyde, whichformaldehyde also would introduce unwanted porosity, as would othervolatiles. Moreover, glycol modification reduces the thermal stabilityof the formulations, and confounding with the high peak processingtemperatures, leads to enhanced porosity and, hence, frost heaving, asin Walls U.S. Pat. No. 3,662,446.

The high peak processing temperatures for the Hindersinn U.S. Pat. No.4,419,400 formulations are necessary to achieve high line speeds,thereby to make the pultrusion process economically viable.

Phenolic laminating resins typically must use acid catalysts or hightemperature post curing or both.

Phenol cures are relatively slow and must be carried out at highertemperatures.

Phenol is relatively easily dissolved and absorbed by body tissue andposes safety hazards to workers.

Formaldehyde now is labeled a carcinogen.

Dailey, Jr. U.S. Pat. Nos. 5,075,413 and 5,075,414 address some of theseconcerns by using resole-novolak mixtures which can be pultruded atlower (160° C.) temperatures. Owing to the physico-mechanicaldegradation of the fiber reinforcement at high pH (>10 pH), the Dailey,Jr. U.S. Pat. Nos. 5,075,413 and 5,075,414 are limited to low pH (<10pH) and consequently suffer from long processing (>0.06 Hour) times.

Greatly advantageous would be a composition or composite resin systemwhich provides a synthetic wood composition, or composite, that has thestructural features and the aesthetic visual appeal of wood, but not theshortcomings of wood or its substitutes as available in the prior artand which could be produced at lower temperatures and high line speeds.

It is an object of the present invention to provide a novel compositesubstitute for natural wood.

It is an object of the present invention to provide a novel compositesubstitute for natural wood having the structural features and theaesthetic visual appeal of wood.

It is an object of the present invention to provide a novel compositesubstitute for natural wood which overcomes the problems associated withwood degradation.

It is an object of the present invention to provide a novel compositesubstitute for natural wood which overcomes the problems associated withfungal and termite attack.

It is an object of the present invention to provide a novel compositesubstitute for natural wood which overcomes the problems associated withthe natural aesthetic defects and shortcomings of natural wood such asknots and warps.

It is an object of the present invention to provide a novel compositesubstitute for natural wood which is free of the non-homogeneousappearance of natural wood caused by defects.

It is an object of the present invention to provide a novel compositesubstitute for natural wood which provides the aesthetic characteristicsof wood and the desired termite and fungal resistance while providingthe fire and flame resistance of the synthetic composites.

These and other objects of the present invention will be described inthe detailed description of the invention which follows. These and otherobjects of the present invention will become apparent to those skilledin the art from a careful review of the detailed description.

SUMMARY OF THE INVENTION

The product and process of the present invention provide a syntheticwood product and method of making, including a plurality of continuousglass fibers oriented substantially in the longitudinal axis, contactingthe fibers with a resorcinol modified resin binder, and pultruding thefibers and binder into a synthetic wood article. In one aspect, thesynthetic wood material is oxidatively treated to restore color. In oneaspect, the fibers and binder are precoated, e.g., such as with afurfuryl alcohol resin, prior to the pultrusion step to form thesynthetic wood.

DETAILED DESCRIPTION

The present invention provides a composition including fire resistantand fungal/termite resistant glass, aramid, or ceramic fibers orfilaments reinforced in fire and fungal/termite resistant phenolic,furanic, or ceramic matrices.

The fibers or filaments of the present invention are processed bypassing the fiber or filament component into a bath or vessel of theliquid resin binder. Then the resin impregnated filament is passedthrough one or more dies having an aperture opening of smaller dimensionthan that of the composite of the resin binder saturated filamentcomponent.

The die operates to wring out excess resin binder and to compress andform the resin binder saturated filament into the predetermined shape ofthe die.

The resin binder impregnated filament is pulled as a continuous strandfrom the pultrusion die.

The composite then can be cured with heat or other curing means.

The pultruded and cured product then can be cut into desired lengths.

When the artificial wood substitutes of the present invention aremachined or cut, the nascent surface has an appearance that is lighterthan the color of the longer-lived surfaces. Thus, the nascent surfaceof the machined or cut artificial wood substitute may be sometimesdifferent from the color of the longer-lived surfaces. Such a differentcolor is a disadvantage because it detracts from the quality of visualappeal of the artificial wood substitutes of the present invention.

Thus, subsequent to forming nascent surface of the artificial woodsubstitutes of the present invention, we have found that it is importantto subject the machined surface to an oxidative treatment. Such anoxidative treatment is provided by a physical or chemical treatment. Anexample of such a physical oxidative treatment is flame treatment.Another example of such a physical oxidative treatment is frictionalrubbing. We have found that flame treatment is particularly advantageousin restoring color. Nevertheless, other treatments such as treatmentwith chemical oxidants are used. Examples of suitable chemical oxidantsare hydrogen peroxide or benzyl peroxide.

We have found that it is important to precoat the substrate beforeimpregnating with resin. The precoating can be provided by a furfurylalcohol resin. The precoating step of the process of the presentinvention provides for a full furfuryl alcohol interaction and fullcoatability of the fibers. It is an important difference that theprecoating step of the process of the present invention avoids anyinteraction wherein the furfuryl alcohol is chemically bound into thebinder network.

The present invention overcomes problems with additions of furfurylalcohol in the resin binder wherein the furfuryl alcohol is tied upchemically in the resin binder, which limits interaction of the furfurylalcohol with the fibers.

The precoating step provides for the ability to use the fibers of thesubstrate of the present invention in hostile chemical environments,high pH, and higher temperatures. The higher temperatures provide forsignificantly higher throughput.

Other precoating materials are provided by coating formulationspossessing high thermal stability, and examples are polyimides.

The composite of the present invention is free of the natural and pestrendered defects associated with natural wood.

Preferably, the fiber or filament is a glass fiber composition, e.g.,such as in one embodiment, an E glass containing low amounts of alkali,high tensile strength, and high elasticity with low elongation. Theglass fibers are sized in the range of about 80 to 100×10⁻⁵ inches indiameter. Bundles of the glass fibers contain a number of glass fibersin the range of about 100 to 5000.

Alternatively, other filaments can be used, e.g., such as filaments madeof graphite, carbon, aramid (Kevlar), filaments of polypropylene orpolyester, and combinations of these filament materials.

The resorcinol modified resin binder used in the present invention is areaction product of a resorcinol and a phenolic resole resin. Theresorcinol modified resin binder of the present invention is availablein a formulation of Resorciphen-2074 made by Indespec ChemicalCorporation of Pittsburgh, Pa.

The synthetic wood appearance is provided by the resin binder of thepresent invention and the way it is reacted. The resin binder of thepresent invention is processed in a way so that it is auto-catalyzed,i.e., the resin binder is allowed to react such that it is contactedwith no external catalyst introduced into the resin binder stock itself.The importance of this difference is that the resin binder of thepresent invention will minimize darkening of the resin binder withcuring.

The resorcinol modified component of the resin binder of the presentinvention provides a reddish hue to the finished article of the presentinvention in a way to simulate the appearance of wood and provide thesynthetic wood article of the present invention.

Unlike prior art processes, the phenolic resin binder of the presentinvention is not acid catalyzed. The importance of this difference isthat the resin binder of the present invention will not corrode a steeldie.

Unlike prior art processes, the phenolic resin binder of the presentinvention does not use a basic, e.g., alkaline catalyst. The importanceof this difference is that the fiber, e.g., glass fiber, of the presentinvention will not be weakened by the presence of the basic catalyst.

The synthetic wood of the present invention is formed by impregnatingthe glass fiber through a resin binder bath to impregnate the fiberglass filaments with resin binder in liquid form. The impregnatedfilaments then are pultruded and cured. The pultruded composite may becut to predetermined lengths to form the synthetic wood articles of thepresent invention.

The synthetic wood articles of the present invention can be produced ina variety of different cross-sectional shapes, e.g., such asrectangular, flat, cylindrical, angular designs, e.g., by way of oneexample such as star shaped, or other designs, e.g., such as oval.

The synthetic wood articles of the present invention can be produced ina variety of finished products, e.g., such as boards, strips, tubes,rods, or sheets.

The product and process of the present invention provide a degradationresistant, strong, and light weight composite as a substitute fornatural wood products.

EXAMPLE I

Glass (E) fiber obtained from Owens Corning Fiberglass Corporation inToledo, Ohio was pultruded at 150° C. with a phenolic resin binder usinga 16 inch steel die at a pulling speed of 5 inches per minute. Theensuing rods were cut to appropriate sizes for evaluation.

To assess the resistance of the composite material to fungal/termiteattack, pieces were vertically partially (half) buried in Murrysville,Allegheny County, Pa. for various durations up to one year along side amoist river bed known to contain termites, using southern pine ofidentical dimensions as a control. After a period of one year, thepieces were dug up for visual inspection. Although they had beensubjected to a time when the river overflowed its banks, followed by asevere snowy winter and a subsequent damp summer, the composite pieceswere visually identical to their unburied equivalents. In contrast, thesouthern pine pieces had grown a white, moldy, stringy substance ontheir surfaces and lacked dimensional and mechanical integrity.

The results show that the composite materials are fungal/termiteresistant and weather resistant.

EXAMPLE II

Glass (E) fiber was obtained from Owens Corning Fiberglass Corporationin Toledo, Ohio. Fibers and resorcinol modified phenolic resin binderwere precoated prior to being pultruded at under 150° C. through a 16inch die at a pulling speed of 5 inches per minute.

The precoating was a furfuryl alcohol resin.

It was found that the resulting pultruded articles were produced at highpH, i.e., greater than 10 pH, and shorter processing times, i.e., lessthan 0.06 hours. It was found unexpectedly that the resulting pultrudedarticles were substantially porosity free.

The process of the present invention forms a synthetic wood material byproviding a plurality of continuous glass fibers oriented substantiallyin the longitudinal axis, contacting the fibers with a resorcinolmodified phenolic resin binder, and pultruding the fibers and binderinto a synthetic wood article.

The process of the present invention precoats the fibers and binder witha precoating resin prior to the pultruding step. The precoating resinincludes furfuryl alcohol resin.

The resorcinol modified phenolic resin binder preferably is cured afterthe pultruding step, e.g., at a temperature of about 25° C. to 150° C.for about 0.1 to 24 hours.

The resorcinol modified phenolic resin binder preferably isauto-catalyzed.

The process of the present invention includes pultruding to produce apultruded article produced at a pH greater than 10.

The present invention includes E-glass fibers as the substrate. In oneembodiment, the fibers are composed of E glass co-mixed with carbon,aramid, or ceramic fibers, or mixtures thereof. The fibers are sized inthe range of about 80-100×10⁻⁵ inches in diameter. The fibers are formedin bundles containing a number of glass fibers in the range of 100 to5000.

The process of the present invention produces a pultruded article whichis substantially porosity free.

In one aspect, the process of the present invention produces a syntheticwood material which is substantially free of the defects of knots,warps, or pores.

The synthetic wood material is formed into a pultruded cylinder, log,rectangle or square. The pultruded shape is cut into lengths of about0.125 inches to 12 inches.

Thus, it can be seen that the present invention accomplishes all of thestated objectives.

Although the invention has been illustrated by the preceding detaileddescription, it is not intended to be construed as being limited to thespecific preferred embodiments employed therein.

Whereas particular embodiments of the invention have been describedherein above, for purposes of illustration, it will be evident to thoseskilled in the art that numerous variations of the details may be madewithout departing from the invention as defined in the appended claims.

What is claimed is:
 1. A process for forming a synthetic wood material,comprising: (a) providing a plurality of continuous fibers selected fromthe group consisting of filaments of graphite, carbon, aramid,polypropylene, polyester, and combinations of filaments of graphite,carbon, aramid, polypropylene, and polyester; (b) orienting said fiberssubstantially in the longitudinal axis; (c) contacting said fibers witha resorcinol modified phenolic resin binder; (d) pultruding said fibersand binder into a synthetic wood article; (e) curing the resorcinolmodified phenolic resin binder after said pultruding step, wherein saidcuring the resorcinol modified phenolic resin binder step isauto-catalyzed; and (f) oxidative treating said synthetic wood article.2. A process as set forth in claim 1 further comprising precoating saidfibers and binder with a precoating resin prior to said pultruding step.3. A process as set forth in claim 1 further comprising cutting saidsynthetic wood material in the shape of a wood board, plank, or strip.4. A process as set forth in claim 1 wherein said oxidative treatingcomprises flame treatment for restoring color.
 5. A process as set forthin claim 2 wherein said precoating resin comprises furfuryl alcoholresin.
 6. A process as set forth in claim 3 wherein said curingcomprises curing at a temperature of about 25° C. to 150° C. for about0.1 to 24 hours.
 7. A process as set forth in claim 6 wherein saidpultruding comprises pultruding to produce a pultruded article producedat a pH greater than
 10. 8. A process as set forth in claim 1 whereinsaid aramid fibers are composed of Kevlar aramid fibers.
 9. A process asset forth in claim 1 wherein said fibers can be co-mixed with ceramicfibers.
 10. A process as set forth in claim 8 wherein said fibers aresized in the range of about 80-100×10⁻⁵ inches in diameter.
 11. Aprocess as set forth in claim 1 wherein said pultruding comprisespultruding to produce a pultruded article which is substantiallyporosity free.
 12. A process as set forth in claim 8 wherein said fibersare formed in bundles containing a number of fibers in the range of 100to
 5000. 13. A process as set forth in claim 1 wherein said pultrudingcomprises pultruding to produce a pultruded article which issubstantially free of the defects of knots, warps, or pores.
 14. Apassivation treated synthetic wood material comprising: (a) a pluralityof continuous glass fibers oriented substantially in the longitudinalaxis; (b) a resorcinol modified phenolic resin binding said fibers toform a synthetic wood material, wherein said synthetic wood article hasbeen oxidative treated to restore color; and (c) wherein said syntheticwood article is formed by the process of providing a plurality ofcontinuous glass fibers oriented substantially in the longitudinal axis;contacting said fibers with a resorcinol modified phenolic resin binder;pultruding said fibers and binder into a synthetic wood article; curingthe resorcinol modified phenolic resin binder after said pultrudingstep, wherein said curing the resorcinol modified phenolic resin binderstep is auto-catalyzed; and oxidative treating said synthetic woodarticle.
 15. A psssivation treated synthetic wood material as set forthin claim 14 wherein said synthetic wood material is in the form of apultruded cylinder, log, rectangle, or square cut into lengths of about0.125 inches to 12 inches.
 16. A passivation treated synthetic woodmaterial as set forth in claim 15 wherein said synthetic wood articlehas been oxidative treated by flame treatment to restore color.
 17. Apassivation treated synthetic wood material as set forth in claim 14wherein said fibers are E glass fibers co-mixed with carbon, aramid, orceramic fibers or mixtures thereof.
 18. A passivation treated syntheticwood material as set forth in claim 14 wherein said fibers are formedinto bundles.
 19. A passivation treated synthetic wood material as setforth in claim 14 wherein said fibers are sized in the range of about80-100×10⁻⁵ inches in diameter.
 20. A process for forming a syntheticwood material, comprising: (a) providing a plurality of continuousfibers selected from the group consisting of the filaments of graphite,carbon, aramid, polypropylene, polyester, and combinations of filamentsof graphite, carbon, aramid, polypropylene, and polyester sized in therange of about 80-100×10⁻⁵ inches in diameter and oriented substantiallyin the longitudinal axis; (b) contacting said fibers with a resorcinolmodified phenolic resin binder substantially free from catalyst; (c)precoating said fibers and binder with a furfuryl alcohol resin; (d)passing the precoated fibers through a steel pultrusion die; (e) curingsaid resorcinol modified phenolic resin binder substantially free fromcatalyst to form a synthetic wood material, wherein said synthetic woodmaterial is substantially free of the defects of knots, warps, or pores;(f) cutting said synthetic wood material in the shape of a wood board,plank, or strip; and (g) oxidative treating said synthetic wood materialby flame treatment to restore color.